i´m drifting but i use marks in the roads .like drains for SO, color changes is grass.dds files in kyotoNational and some other things.
it´s a learning process and like one allready said.. then u have taken one turn 1000times u don´t need it that mutch.
one also said: depending of the tyres etc etc: i have one spot that are the cold tyres, and one for the warm tyres and for me it works.
but like i said.. i´m drifting.. racing should work almost the same i guess.